Cylinders of internal-combustion engines

ABSTRACT

Cylinders of internal-combustion engines, reciprocating-piston or rotary-piston type, made of hypereutectoid aluminum-silicon alloy and formed with a labyrinth of grooves, in checkered or spiral pattern for example, in at least the area of the inner surface along which gastight seal members of the piston slide, said grooves being packed with a dystectic material, such as a ferric alloy, molybdenum, metallic carbide, or ceramic, or a mixture thereof, flush with the rest of the inner surface formed of an aluminum-silicon alloy.

United States Patent 1191 Hamada eta].

[1111 3,808,955 [451 May 7, 1974 Assignee:

CYLINDERS OF INTERNAL-COMBUSTION ENGINES Inventors: Yoshitugu Hamada;Yasunori Nakamoto; Seizo Jinno, all of Nagahama, Japan Yanmar DieselEngine Co., Ltd., Osaka, Japan Filed: Oct. 12, 1972 Appl. No.: 297,092

U.S. c1. 92/169, 123/193 0 1111.01. F0lb 11/02, F02! 1/20 Field ofSearch 123/193 C; 92/169, 170

References Cited I UNITED STATES PATENTS I 2/1938 Sanders 92/169 8/1942Sanders i 92/169 5/1967 Jones 92/169 10/1970 lzumi 123/93 C 3,620,13711/1971 Prasse 92/169 FORElGN PATENTS 0 APPLICATIONS 1,133,041

ll/1956 France 92/169 PrimaryExaminer-Wendell E. Burns Attorney, Agent,or Firm-Ladas, Parry, Von Gehr, Goldsmith & Deschamps 1 ABSTRACT 1 5Claims, 4 Drawing Figures I PATENTEUMAY 7 1974 SHEET 1 0Fv 2 FIG.

Q. xv?

FIG. 2

PATENTED MAY 7 I974 SHEU 2" BF 2 F|ej3 'FIG. 4

This invention relates to cylinders of internalcombustion engines.

For the purpose of the invention the term cylinders means the cases eachsurrounding each piston of an internal-combustion engine and defining aworking chamber or chambers therebetween.

With the view to saving the weight of engines and improving theircooling efficiency to. meet increased power output, it is sometimesattempted at using aluminum alloy cylinders without iron sleeves.Usually in such case a hyper-eutectoid aluminum-silicon alloy is usedwhich contains crystallized silicon in the parent metal. The samematerial has been adopted for the fabrication of side housings ofrotary-piston engines having trochoid-shaped cylinders.

I The hyper-eutectoid aluminum-silicon alloy cylinders, which containhard crystallized sillicon as stated above, are superior in abrasionresistance to the cylinders provided with iron sleeves or chrome-platedon the inner surface, provided that the former is adequately lubricated.

It is known, however, that at the time of cold-weather starting thecylinders of this material tend ,to suffer from objectionable scuffingon the inner surface due to their contact with sliding gastight sealmembers of the pistons. [Refer to Aluminum engine will power minicar,Product Engineering, Apr. 27, 1970, published by Margan-Grampin Inc.,New York, p.54, or Light metal casting and its trends, .IIDOSHA GIJUTSU(Automobile Technology, a Japanese periodical), 26, 4, 1972, p.395.]

The tendency is presumably sttribut'ed to the following facts.

For starting in cold weather the engine must be fed with a rich fuel-airmixture by means of a choke valve. The fuel thus applied in an increasedproportion washes away' lubricating oil from the surface along whichgastight seal members on each piston slide, thereby leading to very poorlubrication of the surface. (Refer to The Vega 2300 Engine, SAE Paper710/47, p.4.)

As the gastight seal members slide on'such surface,

ing the possibility of aforementioned'scuffing. As a result, it has nowbeenfound that the foregoingpurposes can be fulfilled by forming groovesin a certain labyrinth pattern on at least the inner surface portion ofthe cylinder that is subjected to the sliding contact by gastight sealmembers of a pistonand depositing a material having a higher meltingpoint than the aluminumsilicon alloy in the grooves so that the surfaceof the dystectic material filling up the grooves can be flush with therest of the inner surface, i.e., the exposed surface of thehyper-eutectoid aluminumsilicon alloy. The present invention ispredicated upon this. discovery.

The reason for which the scuffing of the inner surface of cylinders incold-weather starting of an engine can be avoided by the constructionabove described is yet to be theoretically clarified. However, itappears most likely that, as the gastight seal members of the pistonmove in sliding contact with the inner. surface of the cylinder, theparticles produced by the abrasion of the dystectic material aredispersed and embedded in the aluminum alloy tomake it resistant toscuffing.

. The invention is illustrated, by way of example, by the accompanyingdrawings in which:

FIG. 1 is a cross-sectional view of a part of a cylinder for areciprocating-piston engine FIG. 2 is a detail of the portion of thecylinder-encir The labyrinth of dystectic material isformed, forex- Iample,by knurling the inner surface of the cylinder,

they no longer formany lubricant film and come into direct contact withthe aluminum alloy surface. .When

this happens, the latter, which is a metal having a relatively lowmelting point, readily fuses and wears partly with the seal material.This wear due to fusion results in scuffing on the surface of thealuminum alloy along which the piston works.

Such an objectionable phenomenon seldom takes place with the materialsas used in the fabrication of iron sleeves that have higher meltingpoints that aluminum alloys.

Naturally the scuffing is precluded by the use of more dystecticmaterials, e.g., molybdenum, metallic carbides, and ceramics.

In view of this, we made numerous experiments on combinations ofhyper-eutectoid aluminum-silicon alloy and various. dystectic materials.The aluminumsilicon alloy is light in weight, easy to cool, andpossesses excellent wear resistance under the operating conditionsexcept for the cold-weather start as already pointed out. Theexperiments were aimed at taking advantage of these features of thealloy and also eliminatthereby forming grooves in a checkered pattern,and spraying a ferrous alloy, molybdenum, metallic carbide, or ceramic,in molten form, over the inner surface, and then removing the resultingdeposit from the area of the inner surface'other than the groovesurface.

FIG. 2 is a micrographic representation of the portion encircled at A inFIG. 1. The structure consists of crystallized silicon 7, ahyper-eutectoid base 9 of silicon and aluminum, and a dystectic material11 deposited on the grooves formed on the inner surface 3 of thecylinder.

FIGS. 3 and 4 illustrates another embodiment of the invention as appliedto a rotary-piston engine having a trochoid-shaped cylinder, FIG. 3showing a rotor housing and FIG. 4 a side housing. T

In FIG. 3 the housing l5'is made of a hyper-eutectoid' aluminum-siliconalloy and has a trochoid-shaped inner 3 4 nular surface surrounds aspiralling loop of a dystectic 2. A cylinder as defined in, claim 1wherein the patmatel'ial 25- tern of the grooves is checkered, striped.dotted. or spi- What is claimed 'is: ral. 1. A cylinder of aninternal-combustion engine char- A cylindar as d fi d claim 1 wherein hacterized by the combination of the following features: 5 stecticmateria} is a ferrous alloy molybdenum a contacttherewith, and.(3) adystectic material having (l) made of a hyper'eutectold alummum'smcontallic carbide, or ceramic, or a mixture thereof.

(2) It formed wlth glooves m a labyrmth H 4. A cylinder as defined inclaim I wherein the cylintern in at least the area of the inner surfacealong wh1ch d t t I b gastight seal members of a piston move in slidingareclpmca mg'pls on m ema us engine.

a higher melting point than the said aluminum-silicon A Cylinder asdefined Clalm 1 h the y alloy is deposited in the grooves and exposedflush with def is a trochoid-shaped cylinder in a ry-pi n the rest ofthe inner surface of the cylinder formed by rna -combust on engine. 5the hyper-eutectoid aluminum-silicon alloy.

2. A cylinder as defined in claim 1 wherein the pattern of the groovesis checkered, striped, dotted, or spiral.
 3. A cylinder as defined inclaim 1 wherein the dystectic material is a ferrous alloy, molybdenum, ametallic carbide, or ceramic, or a mixture thereof.
 4. A cylinder asdefined in claim 1 wherein the cylinder is in a reciprocating-pistoninternal-combustion engine.
 5. A cylinder as defined in claim 1 whereinthe cylinder is a trochoid-shaped cylinder in a rotary-pistoninternal-combustion engine.